Sprinklers and Drippers

Dec 16, 2010 • Andrew Walladge

Much has been written recently regarding the pros and cons of sprinklers and drippers. I’m going to buy into the debate only to point out that the whole idea of irrigation is to deliver water to plant ROOTS efficiently.

Splashing it about and throwing water into the air just can’t do the job as efficiently as well designed drip irrigation systems delivering water just above or at ground level or even under ground for lawns. Thus drippers will leave more water in the river and more money in your pocket.

The main consideration coming into summer after such a wet and cool spring is not so much how you get water to your precious high water use plants but being aware that almost all garden plants will be very ‘soft’ and prone to wilting on the first warm day. The temptation is to whack the watering on to apparently revive them ready for yet another hot day.

Imagine for a moment what is happening below the ground. Plants have spent the past few months developing roots where the moisture has been. That is, right near the surface. This is the area of the soil profile that will dry out first (even in mulched areas). It is also the area, especially with sprinklers, that irrigation will “wet up” first. Therefore these roots that have developed near the surface will be constantly renewed with frequent light irrigation. This in turn leads to soft plants that, yes, you guessed right, the natural urge is to whack the sprinkler on to revive wilting plants on a hot day.

To get off this merry go round of constantly watering and worrying about wilting plants and not wanting to go on holidays or a day trip in summer one needs to think differently about what it is that plants are needing.

Wilting is not necessarily bad and neither is watering necessarily a good or bad thing to be doing. Many soft plants will wilt during the day, only to spring back up at the end of the day. To test what is happening, dig a hole about 30cm deep, about 30 – 40cm from your plant (further away for older and larger plants) and feel if it is moist. If so, put any watering off for a few days and try the feel test again. This process is useful for getting to know how moist the soil actually is. The test will tell you different things for different plants. For example, a lettuce plant will need quite high levels of moisture in the soil to avoid reaching permanent wilting point (the point at which some or all plant cells will not recover – i.e. die!) whereas an indigenous plant (even one that is soft) will cope with quite low soil moisture levels.

Longer and less frequent watering (than you think is required for whatever plant) will also help slow the “watering merry go round”.

Many Australian plants will respond to pruning at this time of year (now) and is a great way to remove soft growth that will be replaced by tough growth ready for summer. This will also promote stronger and deeper root growth.

While it has been a marvellous spring for gardeners in many ways, the warning is that plants are very soft and prone to wilting. Will you reach for the secateurs and spade or the hose and tap?